NSTXNSTX Supported by

NSTX Centerstack Upgrade Project Meeting

P. Titus April 14, 2010

PF4/5 Terminal Stress

Existing PF4/5 Support Weld Algorythm

Moment Influence Coefficients

Bottom “Lid” Torque with Access Holes

PF5 Terminal Analysis16.0 kA in PF4 and 31.8kA in PF5

As of Oct CDR:“We are Still Evaluating the Appropriate Loading Design Basis.

Present Analyses based on Worst Case Currents Provide Conservatisms That Will Be Translated into Cost Savings During the PDR”

For the April 29 Peer Review:

Very few areas are being qualified using maximum power supply loads from the design point.

Qualification is based on Max and Min loads and load combinations for the 96 scenarios from the Design Point

OrMax and min loads, and stresses from an envelope of the Global model results, run for the 96 scenarios.

In addition: All calculations will be required to specify an algorithm for computing critical stresses temperatures etc, for the DCPS to limit.

Currents for Sept 8 Design Point (Exclusive of OH)

-40

-30

-20

-10

0

10

20

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96

data Number

Ter

min

al C

urr

ent (A

mps)

PF1AU

PF1BU

PF1CU

PF2U

PF3U

PF4

PF5

PF1AL

PF1BL

PF1CL

PF2L

PF3L

Machine Protection System Algorithms

PF1,2,3 supports, welds bolts – At this stage, These are just calculated from influence coefficient matrix loads divided by weld or bolt area. Proposing to add Moment Influence Coefficients

PF 4/5 support weldment (see example)PF4/5 Conductor (Titus)

OH Preload-Launch-TF temperature dependencePF1a-OH interaction StressVertical Loads on pedestal load path (TF Flag Bolts, Pedestal hilti’s), (Ali)

TF Strap (T. Willard) – Mostly designed to TF max Current. DCPS should trip if vertical field exceeds limit (.24T?)

TF OOP loads are a Special Problem

Addition of Moment Influence Coefficients to DCPS

Bolt Loads are calculated from the vertical force and the moment divided by the width of the bolt pattern

Bolt Loads are calculated only from the vertical force.

Moment influence Coefficients are calculated about a geometric center of the coil.

Comparison with Ron’s Influence Coefficients

This PF3 support analysis only Included the vertical load on PF3. Moments will add to bolt and weld stress. It is proposed to have the DCPS calculate bolt and weld stresses with the moment applied.

AISC Table 1.17.5 Minimum weld sizes recommended for joined plate sizes.

HM quoted this in his LTX analysis – Why we were concerned with only 1/8 inch structural welds

The torsional moment for design of the lid/flex/diaphragm bolting and the TF steps or keys is 0.3MN-m for the lower lid – Without Holes

PF4U PF5U PF4L PF5L

From FEA 996520 803729 4000 1500

Weld Pa/Newton 996.52 803.729 4 1.5

Weld psi/lb 0.964377 0.814102 0.004052 0.00151936

PF4/5 WeldmentNominal Weld = 5/16 in. QA Effective Weld = 1/4FEA Weld Model Thick =10mm Weld Stress to FEA Stress = (.01*39.37)/.25 = 1.57

Weld Allowables are: 14 Ksi for Visual Inspection 20 ksi for Penetrant Inspection

PF4/5 Support Weldment Strss Algorythm

PF4/5 WeldmentNominal Weld = 5/16 in. QA Effective Weld = 1/4FEA Weld Model Thick =10mm Weld Stress to FEA Stress = (.01*39.37)/.25 = 1.57

~25MPa * 1.57 = 39.25MPa = 5629 psi

Based on the Corner Peak:58 MPa*1.57 = 13274 psi

14 ksi is allowed with only visual inspection

Weique Que told me that the protection system would only allow 18 kA based on my multipliers.

I improved the mesh around the corner –Still has a sharp point, but the stresses are lower.

For 30.8kA this is (31.8/20)^2*(~70) = 176 MPa. Satisfies Copper metal Allowable of 233

Low Modulus Insulation Coil Results (Expect Mylar Slip Plane)

Is cyclic slippage OK for the Mylar?I would use 12 supports

The torsional moment for design of the lid/flex/diaphragm bolting and the TF steps or keys is 0.28MN-m for the lower lid – With Holes -Only slightly less than without.